High-frequency converter apparatus



y 1952 w. w. HANSEN 2,602,137

HIGH-FREQUENCY CONVERTER APPARATUS Original Filed 001;. 25, 1941 FROM OSCILLH TOR DETECTOR INVENTOR I WILLIAM W HAN 5EN ATTORNEY invention.

Patented July 1, 1952 2,602,131 ,r HIGH-FREQUENCY, CONVERTER;

. APPARATUS,"

William Hansen, Stanford University, Calif.

assign'or to The Sperry ration of Delaware Corporation, a corpo- Original applicationoctober 2 3,: 1941, Serial lilo, 416,170. Divided and this application October 29, 1946, Serial No.706,304

- 15 Claims.

The present invention relates to the art including superheterodyne radio receivers and frequency changers especially adapted for use with ultra-high and super-high frequency waves in the portion of the frequency spectrum above 300 megacycles per second, usually termed the microwave region. The present application is a divi- $1011 of parent application Serial No. 416,170, filed October 23, 1941, now Patent No. 2,425,738. I

In conventional receivers, including those of wave differing in frequency relatively slightly from the received wave and yet having good frethe microwave type, it is customaryto use a guency stability in'order that the intermediate frequency shall not vary too widelyq Asdiscussed in the above-mentioned parent application a desirable method for producing 'the local oscillator-frequency is to generate a stabilized lower frequency (such as by a crystalcontrolled oscillator) and to multiply this lower frequency by successive stages to reach the desired microwave frequency. In the prior art, this has necessitated the use of a microwave frequency multiplier for the last multiplication step, in addition to and separate from the tuned microwave mixer'for heterodyning the resultant local oscillator wave with the received wave. According to the present invention, such receiver or frequency changer systems" are greatly simplified by the use of a, single structure serving simultaneously as the microwave frequencymultiplier and as a mixer, thereby reducingthe number ofresonant circuits or cavity resonators in the system. 4

. Accordingly, it is an vention to provide simplified receiver or frequency changer apparatus suitable 'forluse with microwave frequencies.

It is another object of the present invention to provide improved apparatus of the abovementioned type in which the functions of frequency multiplier and detector or mixer are combined.

Other objects and advantages will become object of the present in- I apparent from the following specification taken 1 in connection with the accompanying. single figure of drawing, which is a schematic representation of an electron discharge device and circuit therefor embodying the principles of the present tors. Resonator 3 l is coupled to a source of rela- 1 tively low fundamental; frequency energy (for example, about 300 megacycles'per second) which it is desired to multiply to produce the local-oscillator wave (which may have a' frequency near 3000 megacycles per secondffor-example), this resonator 3 I; being tuned to this-lower frequency. Resonator 3 2, *s epai'ated from resonator 3 l by 'drift tube 35', iscoupled 'tofthe source of; energy which itis desired to'beat against the local oscillator wave, this source being shown illustratively as an antenna-10,,"- 1 Resonator 32 is selective or resonant broadly enough to be excited to oscillationb'oth at frequency 9 of; the received wave'and at the'desired multiple *orf-h'arr'nonic njo of the fundamentalfrequency ft supplied 1 to resonator 3 I. In this way, resonators 3| and32 operate as a frequency multiplier to produce oscillations of frequency nfo in resonator '32, upon'whichosci1- lations are superposed the oscillations of received frequency f derived' fro'm antenna 20 or "other source used in place -thereof.. Resonator 31 is tuned in the same manner as-resonator 32 and provides a, stage of amplificationforboth waves offfrequencies f and nfo'. d Locatedin'thepath of the electron stream beyond resonator 31 is a detector structure having apair of slanted "grids 41 maintained at a lpotentia'lnear that of cathode 21 by their connection to a suitable. tap onaccelerating voltage source 23 and aeplate or detector electrode 48 locatedin'the stream pathbeyond grids 41. Plate 48 is coupled" to: a tuned-circuit 4| tuned to thedesired intermediate (frequency, whichin this case is equal =,to-thedifference-between the received frequency 'f .;and the'multiple Me ofthe fundamental frequency: input in. -,'Ihes1a nted grids act-to deflect lower-velocity electrons from their path generally along. the tubeaxis and to collect a considerable percentage .ofsuch electrons. The higher-velocity, electrons- -proceed through grids flywith substantially lessdeflec- :tion. or path bending; and impingeiupon-plate -or collector:electrode, to; be collected there.- by. The elements 41; and 48 thus cooperate as a sensitive electron velocity -;.discriminator system, with non-linear responsiveness to the electron beam as; a function of; electron velocity. W en. o era edt ro ndrotqnl l or t a n ative bias voltage, plate 48 itself performs as a non-linear velocity discriminator, but with less sensitivity and sharpness of velocity selectivity than when used in conjunctionwith the, biased slanted grids 41. I a a As the electron velocity in the stream beyond resonator 31 varies as the resultant of a subwaveform has substantially-the charactenofa wave of frequency nfo modulated by a signalwhose frequency is equal to the difference between f and M0. The electron current collected by plate 48, and hence applied to termediate frequency system 4| varies none in the intermediate frequency amplifier input circuit, corresponding to the demodulation or detection; of the above-described waveform, and thus having its principal component equal in frequency to'the difference between Mo and f. The tuned circuit 4| serves as a filter across which appears the intermediate frequency wave, which may besupplied to anamplifier and detector 25 to actuate a telephone receiver 43 or other type of signal utilization device in conthe tuned in:

4 generated electromagnetic wave to the other of said resonators, and'means for detecting the resultant velocity variations of saidbeam, wherein an intermediate, frequency output may be derived from said detecting means: l

2. Apparatus as in claim 1 wherein said means for applying a locally generated wave includes a stantial velocity modulation component at frequency nfo and a generally weakerveloc'ity' node ulation component at frequency f, the velocity" coupling loop.

3. .A'receiver as in claim 1 wherein one of said resonators has a resonant frequency substantially equal to a harmonic; of that of the other of said ,'1'esonators,.said received electromagnetic wave having afrequency which differs from said harmonic by an amount equal to said intermediate frequency," whereby said produced intermediate frequency is equal to the difference frequency of linearly in response to these resultant velocity variations, so that it yields a net output voltage,

ventional manner. Indicator 45 may be utilized to line up and tune the various'stages o'ftube 33, using the local oscillations derived from line 29 for this purpose. a q

In operation, the electron stream leaving resonator 31 has current components .of frequencies f andnfo. The detector 41, 48 beats these currents to produce adifference orintermediate frequency whichexcites' the tuned circuit li to actuate the receiver or utilization device 43.

Accordingly, the single electron discharge de- I vice 33 simultaneously operatesas a frequency multiplier, as an added stage-of amplification, and-as a mixedor detector thereby permitting relatively simple operation in superheterodyne receptionorafrequencyconversion for waves in the microwave region of the frequency spectrum. According to a modified arrangement, resonator 3| is tuned to frequency f0, resonator 32 is tuned to frequency 7 and resonator 31 is tuned either to frequency nfo or broadly'enough to oscillate both at frequency 'nfo and at frequency ,f. In this arrangement, resonators 3| and 31 operate as a frequency multiplier to produce a beam current component of frequency TLfo. Resonators 32 and 37 may operate as an amplifier to produce a beam current component of frequency 1. Thenthe detector produces the beat or intermediate frequency, as before;

Since many changes could-be made in the above construction and many apparently widely different embodiments of this inventioficould be made without departingfrom the-scope thereof, it is'intende'd that all matter contained inthe above description or shown in the accompanying drawings shall be interpreted-as illustrativeand not in a limiting sense.

Whatis claimed'is: I j 1. A receiverfor high 'frequencywavescomprisin means including an electron emitter for producing "an electronbeam, means for varying beam, meansjfor applying a received wave to-one of said resonators; means for applying locally said received wave frequency and an integral multiple of said local wave frequency.

4. A'receiver for high frequency waves comprising electron dischargetube means for forming an. electronbeam-apair of cavity resonators each having an electron-permeable gap, said gaps being disposed to receive said electron beam, means forsupplying a received wave to one-of said resonators to-velocity var-y the-electrons of said beam at the frequency of said received wave, means forzsupplying .a locally generatedelectromagnetic wave to the'other of, said resonators to furtheriv elocity vary the electrons of said beam predetermined intermediate frequency from a multiple-of said first resonant frequency wherein the frequency multiplication factor is an integer greater-than one, means for. producing an; electron beam, first electrode means positioned along the path of said beam and coupled-to said first resonant circuit, second electrode means positioned along the path ,of said beam beyond said first electrode means with respect to said means for producingan electron beam and coupled to said second resonant, circuit, whereby said resonant circuits are adapted to vary the velocity of'theelectrons of said beam means. for applying a received wave-of said second'resonant frequency to said second resonant circuit, means for applying a locally-generated wave of saidfirst res.- onant frequency to said first resonant circuit, means for detectingtheresultant velocity varia. tions of said beam ,,-a nd means connected .to said vcletectingmeans for deriving an output therefrom at said predetermined intermediate frequency. 1

7. Apparatus as'inclaim fiiwhereinnsaid first and second resonant circuits area pair of cavity resonators. 3 T, w "/11 8. A receiver "for "high; frequency :wav'e's oomprising a first cavity-:rsonator having a'first resonant frequency, asecond cavity resonator having a second'resonantfrequency and having a frequency characteristic of a predetermined band Width, means-for producing an electron beam,

said resonators being adapted to maintain standing electromagnetic waves therein and' h'aving tions of said beam for deriving therefrom an in-,

termediate frequency signal equal to the difference between said harmonic and said received wave frequency.

9. Apparatus as in claim 8 wherein said second resonant frequency is a multiple of said first resonant frequency.

10. Apparatus as in claim 8 wherein said second resonant frequency differs from a multiple of said first resonant frequency by an amount equal to said'intermediate frequency.

11. Apparatus as in claim 8 wherein amplifying means are included, said amplifying means comprising a cavity resonator having a frequency characteristic of said predetermined band width,

and interposed between said second resonator and said detecting means.

12. A receiver for high frequency waves comprising means for producing an electron beam; first, second and third cavity resonators positioned in cascade for successive interaction with said beam; said resonators each having an electron-permeable region disposed along the path of said beam, said first resonator having a selected resonant frequency, means for supplying a locally generated electromagnetic wave to said first resonator, one of said second and third resonators having a frequency characteristic of a predetermined bandwidth, means for applying an electromagnetic wave having a frequency different from the frequency of said locally generated wave to said second resonator, said predetermined bandwidth including a frequency equal to the frequency of said applied wave and also including a-frequency equal to a harmonic of said selected resonant frequency, and means for detecting the resultant velocity variations of said beam, whereby an intermediate frequency output may be derived from said detecting means.

wave and also includharmonic of said first said electron beam to successively 13. Apparatus as in claim 12 wherein said second resonator has a resonant frequency equal to a harmonic equal to said first resonant frequency, said third cavity resonator having said frequency characteristic of said predetermined bandwidth, whereby said first and third resonators function as a multiplier and said second and third resonators function as an amplifier.

14. Apparatus as in claim 12 wherein both said second and third cavity resonators have frequency characteristics of said predetermined bandwidth, whereby said first and second cavity resonators function as a multiplier and said second and third cavity resonators function as an amplifier.

15. A receiver for high frequency waves comprising means fcr producing an electron beam, a first cavity resonator having a first resonant frequency, a second cavity resonator having a second resonant frequency differing from said first resonant frequency, a third cavity resonator having a thirdresonant frequency harmonically related to said first resonant frequency, said cavity resonators being arranged in cascade for successive interaction with said electron beam, means for coupling a locally generated wave to a first resonator, means for coupling a received wave to said second resonator, and means including velocity-selective means located in the path of said beam-for detecting the resultant velocity variations of said beam for deriving therefrom an intermediate frequency signal equal to the difference between said third resonant frequency and. said received wave frequency.

WILLIAM W. HANSEN. REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,190,515 Hahn Feb. 13, 1940 2,260,844 Thomas Oct. 28, 1941 2,281,935 Hansen et al May 5, 1942 2,293,151 Linder Aug. 18, 1942 2,403,025 Samuel July 2, 1946 2,406,370 Hansen et al. Aug. 27, 1946 2,409,608 Anderson Oct. 22, 1946 2,410,840 Samuel Nov. 12, 1946 2,411,289 Mouromtseif et al. Nov. 19, 1946 

